How do i unlock my account password for my acer mini labtop?

well my little brother was playing some games on my labtop then after he was done he went & changed my password & 4got it so now i kant log in to my account & its the only account i made on my labtop so i was wondering if there was a way if i can get passed it somehow & reset my password without downloading any password recovery tools or anything like that any HELP will be appreciated(: thankss